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ISC Small 1/2” Spring Block

 ISC Small 1/2”  Aluminum Arborist Block  The upper sheave and screw are captive - no chance of losing pieces in the tree.
ISC Small 1/2 Aluminum Spring Block image

ISC Small 1/2” Aluminum Spring Block

Buy ISC Small 1/2” Aluminum Spring Block

Block w/ 1/2” x 4’ Loopie

The ISC small arborist block is a great tree rigging block for professional use. The block is secured with a spring-lock. To open, the user simply pushes the pin in, twists, and the sideplates may be swung open. The upper bushing and pin are retained, so they can't fall out during use.

The block accepts rigging ropes of up to 1/2” diameter, and tree rigging slings up to 3/4”. The load rating on the block is 22,480 lb MBS (106 kN), with a WLL of 4,400 lb at a 5:1 design factor. The surfaces of this block are rounded to be more rope-friendly. The sheaves are larger than other 3/4” block for a better bend radius in your rigging lines.

Purchase this kit as a package with a 1/2” x 2’-4’ Loopie sling and save.


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Additional Features

  • Oversized upper sheave accepts 3/4” slings
  • Captive upper sheave with spring-lock
  • Wide bend radius on lower sheave
  • Improved machining for rope-friendly surfaces
  • Sintered bronze bushings
  • Powder-coated side plates
Made in: UK
MBS: 22,480 lb / 106 kN
WLL (5:1) / (10:1): 4,500 lb / 2,000 kg
Max Rope Diameter:1/2”
Max Sling Diameter: 3/4”
Sideplate Material:Powder-coated aluminum
Sheave Material:Aluminum
Axle Material: Stainless Steel
Height: 7.5”
Width: 3.875”
Weight: 3.5 lb / 1,6 kg

Each ISC Small 1/2” medium arborist block is individually serial-numbered.


  • CE Approved

ANSI Z133-2017

The American National Standards Institute (ANSI) has released the ANSI Z133 safety requirements which apply to arboriculutral operations. Components of a rigging system must be used within their Working Load Limits.

ISC blocks are ANSI compliant when used within the manufacturer Working Load Limits.

A green log weight chart (found in the Samson Rigging Wheel) will aid in determining loads in tree rigging.

The full ANSI Z133 safety requirements are available on our tree care standards page.

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